Speaking to BBC Radio 4, her husband Jeremy said: "When the vet opened up his stomach, she found cubes of meat - some sort of beef-like steak - and they had been sewn up with poison inside.

"She thinks there were possibly two or three types of poison.

"I think she identified one as a slug killer. I would guess that the other would turn out to be a rat poison or some industrial type of poison."

He said he did not believe the attack was targeted but he did not think the culprit would be caught.

He said: "They will hopefully try with the CCTV they have in the halls at Crufts but I don't think they will be able to find anybody."

Image copyrightPAImage caption
Jagger's owner, Jeremy Bott, said the NEC would check its CCTV but he did not believe the culprit would be caught

The couple's daughter, Amy Nettleton, said: "The accessibility of shows such as Crufts... is such that the general public can wander in and out of the dogs' benches and approach any dog, so to keep an eye on everybody who came up and spoke to the dogs is very difficult."

Ms Nettleton described her family as "just devastated and beside themselves".

"The sensationalisation that the media has portrayed today - that Jagger was worth £50,000 - is beyond ridiculous," she said.

"Jagger, to his family, was priceless and he was also used, not only as a family pet but as pet therapy."

She said his owners took him into elderly care homes.

"He would sit there and give the residents some delight in him just being around."

The Kennel Club said it was awaiting a toxicology report from Belgian police. It said it had not received any other reports of sickness in dogs at Crufts.

'The biggest in the world'

Image copyrightPA

Crufts is run by The Kennel Club, the UK's largest organisation dedicated to pedigree and crossbreed dogs

It brands the annual event as "the world's largest dog show"

Almost 21,500 dogs competed this year at Birmingham's Genting Arena, among them 2,987 dogs from overseas

The show began in 1891

Knopa, a Scottish Terrier (pictured above), was awarded the prestigious Crufts Best in Show title on Sunday

The winner of Best in Show gets £100 - The Kennel Club said the prestige was more important than the prize money

The club said a show-class Irish setter puppy could sell for "hundreds of pounds"

Ms Lauwers wrote on her Facebook page: "To person who has done it, hope you can sleep well knowing you have killed our love, family member and best friend to our son."

Image copyrightDee Milligan-BottImage caption
Co-owner Dee Milligan-Bott said she did not think a fellow competitor was responsible

Her husband Willem said she was due to give a statement to police later.

Caroline Kisko, Kennel Club secretary, said: "The Kennel Club is deeply shocked and saddened to hear that Jagger the Irish setter died some 26 hours after leaving Crufts.

"We have spoken to his owners and our heartfelt sympathies go out to them.

"We understand that the toxicology report is due and until that time, we cannot know the cause of this tragic incident. "

Image copyrightGetty ImagesImage caption
The Kennel Club, which organises Crufts, said it was "deeply saddened" to hear the news about Jagger

TV presenter Clare Balding, who had been hosting Channel 4's coverage of the event, tweeted: "Everyone at #Crufts2015 horrified at death of Irish Setter Jagger & post-mortem found poison. Awful for all concerned."

Vet Steve Leonard said such incidents were "thankfully rare".

"Obviously they have found a foreign substance in the dog's stomach," he said.

Human forensic techniques would probably be used to establish what the substance was, he said, as such testing went beyond what vets would normally deal with.

"Your heart goes out to the poor owner and what they must be going through," he said.

West Midlands Police said officers had not received any complaint "at this stage" or been asked to investigate an allegation involving the death of a dog in Belgium.

A police spokeswoman said: "If, following toxicology results in Belgium, the force is formally asked to conduct inquiries into the circumstances surrounding the death of the animal, an investigation will take place by officers in conjunction with Crufts and the NEC."